Ionis said its partner Biogen shared topline results from the Phase 2 CELIA study of diranersen (IONIS‑MAPT_Rx/BIIB080), an investigational antisense oligonucleotide targeting tau in early Alzheimer’s disease.
CELIA enrolled 416 participants with mild cognitive impairment due to Alzheimer’s disease or mild AD dementia; all participants had not previously received anti-amyloid therapy. According to the company, the results provide the first randomized Phase 2 evidence of a tau-directed therapy demonstrating both robust biomarker impact and cognitive benefit.
Pre-specified analyses of cognitive endpoints showed slowing of clinical decline across all studied doses, particularly at the lowest dose of 60 mg administered every 24 weeks.
Diranersen produced robust reductions in cerebrospinal fluid tau and in tau pathology measured by PET across all doses, with reductions maintained through the dosing period.
CELIA did not meet its primary endpoint assessing dose response for change from baseline on the Clinical Dementia Rating–Sum of Boxes at week 76. The safety and tolerability profile was generally consistent with Phase 1b, with adverse event rates comparable across dose groups and a higher incidence of serious adverse events at the highest dose. Biogen plans to advance diranersen to registrational development and will present data at AAIC 2026 and other scientific meetings.
